I have followed your procedure, and can confirm that I get the same problem. We shall investigate further and fix for the next firmware release.
In addition…
On investigation it has been found that the error is all about adding an external input source to one of the mixes. If this external input source has no mic-pre (i.e. USB, SigGen, I/O Port In and Rack FX), then it is possible to induce this error. A yellow triangle in the south toolbar will appear, the source selection will need to be changed to clear this error.
Well. I don’t understand it. You should go to 1.20. There are a lot of fixes and improvements.
The bugI posted is fatal for you GLD and you have to reboot in factory settings. True. That is why I posted it. As long as you don’t use Ext In option in a bus you are fine (I think only a few users know and use this option)